U.S. patent application number 13/425519 was filed with the patent office on 2013-09-26 for methods and apparatus for resource sharing for voice and data interlacing.
This patent application is currently assigned to Raytheon Company. The applicant listed for this patent is James F. Keating, Timothy S. Loos, David R. Peterson, David F. Ring. Invention is credited to James F. Keating, Timothy S. Loos, David R. Peterson, David F. Ring.
Application Number | 20130252563 13/425519 |
Document ID | / |
Family ID | 49212274 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130252563 |
Kind Code |
A1 |
Peterson; David R. ; et
al. |
September 26, 2013 |
METHODS AND APPARATUS FOR RESOURCE SHARING FOR VOICE AND DATA
INTERLACING
Abstract
Methods and apparatus for voice and data interlacing in a system
having a shared antenna. In one embodiment, a voice and data
communication system has a shared antenna for transmitting and
receiving information in time slots, wherein the antenna can only
be used for transmit or receive at a given time. The system
determines timing requirements for data transmission and reception
and interrupts data transmission for transmission of speech in
selected intervals while meeting the data transmission timing and
throughput requirements. The speech can be manipulated to fit with
the selected intervals, to preserve the intelligibility of the
manipulated speech.
Inventors: |
Peterson; David R.; (Fort
Wayne, IN) ; Loos; Timothy S.; (Fort Wayne, IN)
; Ring; David F.; (Fort Wayne, IN) ; Keating;
James F.; (Fort Wayne, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Peterson; David R.
Loos; Timothy S.
Ring; David F.
Keating; James F. |
Fort Wayne
Fort Wayne
Fort Wayne
Fort Wayne |
IN
IN
IN
IN |
US
US
US
US |
|
|
Assignee: |
Raytheon Company
Waltham
MA
|
Family ID: |
49212274 |
Appl. No.: |
13/425519 |
Filed: |
March 21, 2012 |
Current U.S.
Class: |
455/83 ; 704/201;
704/E19.001 |
Current CPC
Class: |
H04B 1/48 20130101; H04B
2001/485 20130101; G10L 19/167 20130101; G10L 25/78 20130101 |
Class at
Publication: |
455/83 ; 704/201;
704/E19.001 |
International
Class: |
G10L 19/00 20060101
G10L019/00; H04B 1/44 20060101 H04B001/44 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0001] The invention was made with government support under
Contract No. W15P7T-06-D-E402-0090. The government has certain
rights in the invention.
Claims
1. A method, comprising: a voice and data communication system
having a shared antenna for transmitting and receiving information
in time slots, wherein the antenna can only be used for transmit or
receive at a given time, determining timing requirements for data
transmission and reception; interrupting data transmission for
transmission of speech in selected intervals while meeting the data
transmission timing and throughput requirements; manipulating the
speech to fit with the selected intervals, to preserve the
intelligibility of the manipulated speech.
2. The method according to claim 1, further including compressing
the duration of the speech.
3. The method according to claim 1, further including limiting data
interruption to a predetermined duration.
4. The method according to claim 1, further including employing
independent receivers or transmitters.
5. The method according to claim 1, further including employing
shared receivers and/or transmitters.
6. The method according to claim 1, further including employing
separate antennas.
7. The method according to claim 1, further including limiting
downlink voice interruption to a predetermined amount.
8. The method according to claim 1, including sensing the presence
of speech to determine what segments of the audio input may be
discarded without degrading intelligibility.
9. A system, comprising: an antenna; a voice and data communication
system sharing the antenna for transmitting and receiving
information in time slots, wherein the antenna can only be used for
transmit or receive at a given time; a data/voice timing control
module to determine timing requirements for data transmission and
reception and to interrupt data transmission for transmission of
speech in selected intervals while meeting the data transmission
timing and throughput requirements; and a speech analysis and
control module to manipulate the speech to fit with the selected
intervals, to preserve the intelligibility of the manipulated
speech.
10. The system according to claim 9, wherein the manipulated speech
is compressed.
11. The system according to claim 9, wherein the data interruption
is limited to a predetermined duration.
12. The system according to claim 9, further including independent
receivers and/or transmitters.
13. The system according to claim 9, further including shared
receivers and/or transmitters.
14. The system according to claim 9, further including separate
antennas.
15. The system according to claim 9, wherein the data is source and
sinked by a navigation system.
16. The system according to claim 9, further including a data
encoder and a data decoder for the data.
17. The system according to claim 9, further including a
transmit/receive switch coupled to the antenna.
18. A system, comprising: an antenna; a speech source, a speech
sink, a data source, and a data sink; a transmit/receive/switch
coupled to the antenna; a speech analysis and control module
coupled to the speech source; a data/voice timing control module
coupled between the speech analysis and control module and the
transmit/receive/switch; a transmit switch coupled to the
data/voice timing control module, the speech analysis and control
module, and a RF transmit module, which is coupled to the
transmit/receive/switch; a speech demodulator coupled to the speech
sink; a RF receive module coupled to the speech demodulator, a data
decoder, and a time division control module, which is coupled to
the data/voice timing control module; a data encoder coupled to the
data source, the time division control module, and data/voice
timing control module, wherein the data decoder is coupled to the
data sink.
Description
BACKGROUND
[0002] As is known in the art, voice and data can be communicated
using a variety of equipment. Typically, separate radios are used
for each function to provide independent operation. However, in
some applications space, weight, power, and cost are extremely
limited which can be problematic in providing desired
functionality.
[0003] Sufficient redundancy exists in speech such that even if
some portion of a speech waveform is lost, intelligible speech may
still be conveyed to the listener. Also, many data links are
designed to provide acceptable performance in the event that some
of the messages are missed. One example is Air Traffic Control
voice operating concurrently with an Air Traffic Landing data
link.
[0004] FIG. 1 shows a prior art system 10 having independent voice
and data radios 12, 14 that operate in a half-duplex mode. The
first radio 12 is coupled to an antenna 16 and a voice sink 32 and
a voice source 34. Similarly, the second radio 14 is coupled to an
antenna 26 and to a data sink 22 and a data source 24.
[0005] Note that when a receiver is connected to its antenna, the
corresponding sink receives its information, and conversely, when
the transmitter is connected to its antenna, it can accept
information from the corresponding source and send it out the
antenna.
SUMMARY
[0006] Exemplary embodiments of the invention provide methods and
apparatus for incorporating voice and data in a radio having one or
two receivers and one transmitter. While exemplary embodiments of
the invention are shown and described in conjunction with
particular configurations, applications, and components, it is
understood that embodiments of the invention are applicable to
communication systems in general in which it is desirable to share
transmit and/or receive resources.
[0007] In one aspect of the invention, a method comprises a voice
and data communication system having a shared antenna for
transmitting and receiving information in time slots, wherein the
antenna can only be used for transmit or receive at a given time,
determining timing requirements for data transmission and
reception, interrupting data transmission for transmission of
speech in selected intervals while meeting the data transmission
timing and throughput requirements, and manipulating the speech to
fit with the selected intervals, to preserve the intelligibility of
the manipulated speech.
[0008] The method can further include one or more of the following
features: compressing the duration of the speech, limiting data
interruption to a predetermined duration, employing independent
receivers or transmitters, limiting downlink voice interruption to
a predetermined amount, and/or sensing the presence of speech to
determine what segments of the audio input may be discarded without
degrading intelligibility.
[0009] In another aspect of the invention, a system comprises an
antenna, a voice and data communication system sharing the antenna
for transmitting and receiving information in time slots, wherein
the antenna can only be used for transmit or receive at a given
time, a data/voice timing control module to determine timing
requirements for data transmission and reception and to interrupt
data transmission for transmission of speech in selected intervals
while meeting the data transmission timing and throughput
requirements, and a speech analysis and control module to
manipulate the speech to fit with the selected intervals, to
preserve the intelligibility of the manipulated speech.
[0010] The system can further include one or more of the following
features: the manipulated speech is compressed, the data
interruption is limited to a predetermined duration, independent
receivers and/or transmitters, the data is source and sinked by a
navigation system, a data encoder and a data decoder for the data,
and/or a transmit/receive switch coupled to the antenna.
[0011] In a further aspect of the invention, a system comprises an
antenna, a speech source, a speech sink, a data source, and a data
sink, a transmit/receive/switch coupled to the antenna, a speech
analysis and control module coupled to the speech source, a
data/voice timing control module coupled between the speech
analysis and control module and the transmit/receive/switch, a
transmit switch coupled to the data/voice timing control module,
the speech analysis and control module, and a RF transmit module,
which is coupled to the transmit/receive/switch, a speech
demodulator coupled to the speech sink, a RF receive module coupled
to the speech demodulator, a data decoder, and a time division
control module, which is coupled to the data/voice timing control
module, and a data encoder coupled to the data source, the time
division control module, and data/voice timing control module,
wherein the data decoder is coupled to the data sink.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing features of this invention, as well as the
invention itself, may be more fully understood from the following
description of the drawings in which:
[0013] FIG. 1 is a schematic depiction of a prior art data and
voice communication system having multiple antennas;
[0014] FIG. 2 is a schematic representation of a data and voice
communication system sharing an antenna for receiving and
transmitting;
[0015] FIG. 2A is a schematic representation of an exemplary
aircraft having data and voice communication system to communicate
with an air traffic control system on a vessel;
[0016] FIG. 3 is a block diagram of an exemplary data and voice
communication system sharing an antenna for receiving and
transmitting;
[0017] FIG. 4 is a timing diagram showing uplink and downlink
messages and the unoccupied time available for voice;
[0018] FIG. 5 is a diagram showing a VHF Data Broadcast (VDB)
communication burst;
[0019] FIG. 6 is a diagram showing data communications and
potential voice interruption intervals; and
[0020] FIG. 7 is an exemplary timing diagram for transmitting
speech.
DETAILED DESCRIPTION
[0021] FIGS. 2 and 2A show a radio system 100 on a vehicle 50 to
enable data and voice communication between first and second
systems. In one embodiment, the radio system 100 is attached to an
aircraft 50, such as a helicopter, to enable the exchange of voice
and data between the aircraft 50 and an air traffic control system
70 and a data system 80 for landing, which can be located on a ship
60 or on the ground.
[0022] The radio system 100 includes an antenna 102 that is shared
by a data/voice transmitter 104, a voice/data receiver 108. The
data/voice transmitter 104 is selectively coupled to a data source
110 and a voice source 112 by a first switch 109. A voice sink 116
is coupled to the voice receiver port of the receiver 108 and a
data sink 118 is coupled to the data port of the receiver 108. A
second switch 111, which is independent from the first switch 109,
has a first position to connect the antenna 102 to the data/voice
transmitter 104 and a second position to connect to the
interconnected inputs of the data/voice receiver 108.
[0023] In this configuration, only one of the sources of
information 110, 112 can use the transmitter 104 at one time so
that time sharing of the transmitter is needed. It is assumed that
both RF channels to the ship 60 are available, but that the
transmitter needs to be shared between the sources. In this case a
transmitted signal is interrupted by the higher priority source
when a conflict occurs.
[0024] The architecture of the radio system 100 inhibits reception
for both sinks whenever one of the sources needs to transmit. In
this configuration, the restriction is permanent, but similar
limitations apply, if the isolation provided by the equipment for
the two simultaneous channels is insufficient. This could occur for
fixed frequency operation, if the frequency assignments happen to
be chosen to be too close together, or it could occur if the
frequencies become too close due to the hopping waveforms selected.
In the latter case, these restrictions apply only to the interval
of time for which the signals conflict with each other. For this
configuration transmissions may also be interrupted, depending on
how priorities are defined. The system 100 determines how to
receive sufficient data while allowing transmission of voice.
[0025] In one embodiment, data is communicated as part of a landing
system for an aircraft, such as the Joint Precision Approach and
Landing System (JPALS). As is known in the art, JPALS is a secure
all-weather landing system based on real-time differential
correction of a GPS signal with a local area correction message. An
onboard receiver compares the current GPS-derived position with the
local correction signal to derive a highly accurate
three-dimensional position to facilitate all-weather approaches via
an Instrument Landing System (ILS)-type display.
[0026] FIG. 3 shows an exemplary system 300 having voice and data
interlacing in accordance with exemplary embodiments of the
invention. An antenna 302 is coupled to a transmit/receive switch
304 to control access to the antenna. When Push-to-talk is
initiated, a voice path is set up from a speech source 306, such as
a microphone to transmit, for example, a pilot's voice. This signal
is coupled to a speech analysis and control module 308. The speech
analysis and control module can speed up speech, for example, to
fit speech within certain time intervals while ensuring speech
intelligibility. A data/voice time control module 310 controls a
transmit switch 312 and the transmit/receive switch 304 to control
the transmit paths and receive paths. An RF transmit module 314
processes speech from the speech analysis and control module 308 or
data from the data encoder 326 for modulation on an RF carrier and
input into the transmit/receive switch and transmission by the
antenna 302.
[0027] Information received by the antenna 302 is provided to the
transmit/receive switch 304, which is coupled to an RF receive
module 316. A receive speech path extends from the RF receive
module 316 to a speech demodulator 318, which is coupled to a
speech sink 320 such as a speaker. A data receive path extends from
the RF receive module 316 to a data decoder 322, which is coupled
to a data sink of a navigation module 324. As described more fully
below, navigation data is exchanged between an aircraft and an air
traffic control system as the aircraft comes in for landing, for
example.
[0028] The navigation module 324 includes a data source to provide
data to a data encoder 326. A TDMA (time division multiple access)
timing control module 328 is connected between the data encoder 326
and decoder 322 to send control information to the transmit switch
312. As described more fully below, the radio 300 enables voice and
data communication over a shared antenna to meet data timing
requirements and provide intelligible speech with limited slot
availability. For example, a pilot can activate a push-to-talk
(PTT) system in which speech is stored until it can be transmitted
during intervals selected to allow the data transmission
requirements to be met. The stored speech can be sped up,
interrupted, or otherwise manipulated while maintaining
intelligibility.
[0029] In one particular embodiment, data corresponds to data for
an aircraft landing system, such as JPALS, and voice corresponds to
voice for a pilot to communicate with an air traffic control
system. It is understood that an exemplary embodiment of the
invention using JPALS and Air Traffic Control (ATC) communication
is used to facilitate an understanding of the invention and is not
intended to limit the scope of the invention in any way. Other
voice and data applications with shared antennas will be readily
apparent to one of ordinary skill in the art and well within the
scope of the claimed invention.
[0030] Table 1 below shows exemplary JPALS Data and ATC Voice
Formats that identify pairs of waveforms. The voice formats are
analog AM voice and the data formats are either Gaussian Minimum
Shift Keying (GMSK) or Differential 8-ary Phase Shift Keying
(D8PSK) modulation. In addition alternative voice formats and data
formats are contemplated. SRGPS refers to shipboard relative GPS,
LAAS refers to Local Area Augmentation System, and VDB refers to
VHF Data Broadcast.
TABLE-US-00001 TABLE 1 Data and Voice Simultaneity Formats Data
Format Voice Format JPALS SRGPS Index 1 UHF AM FJPALS SRGPS Index 2
UHF AM (non-hopped) JPALS LAAS (VDB) VHF AM
[0031] FIG. 4 shows uplink and downlink transmissions for JPALS
SRGPS Index 1 and 2 Formats for a single aircraft. The Uplink Slots
(ULS) are receive slots and the downlink are transmit slots for the
aircraft. In the illustrated embodiment, all aircraft listen to the
uplink messages, but until an aircraft is within 60 nautical miles,
it only listens to the 200 nautical mile Uplink Broadcast 400, a 26
ms message once per second. After logging in to the so-called
Surveillance Net, the aircraft listens to the Relative Navigation
Uplink 402, which is a 16 ms message 5 times per second. When it
transitions to Precision Surveillance, it adds the Precision
Approach Uplink message 404, a 20 ms message 5 times per second and
the Ship Motion 20 Hz Uplink 406 a 4 ms message 20 times per
second. Even monitoring these messages, the white space in FIG. 4
shows considerable time when the aircraft does not need to listen
for messages.
[0032] When the JPALS airborne protocol is not logged into the
JPALS Network there will be no transmissions until the aircraft
attempts to enter the Surveillance Net, about 60 nm from the ship
(or on deck before takeoff). When the 60 nm boundary is crossed (or
upon power-up), the aircraft sends a Login Request message 408
comprising a single transmission of 3 to 5 ms in duration. If the
aircraft receives a positive response, it begins to transmit a 6 to
9 ms Surveillance Downlink Message 410 once per second. If it does
not receive a response in 3 seconds, it waits 1 to 10 seconds and
repeats the single transmission 408. If it receives a "No resources
available" response, it repeats the request 408 every 20 seconds
until a time slot allocation or a logout command is received.
[0033] When a Surveillance Login is complete (following a positive
response), the aircraft continues to transmit message 410 once per
second, until the aircraft reaches 10 nm from the ship and it
requests a Precision Surveillance Login. In addition, as commanded
by the ship, the aircraft transmits a 7 to 11 ms message as an ATM
function message 412, but only when the aircraft is logged into the
Surveillance Net (not the Precision Surveillance Net). It continues
the once per second transmissions until it receives a Precision
Surveillance time slot allocation and Precision Surveillance Login
is complete. When Precision Surveillance Login is complete, a
communication system, such as ARC-231, adds five additional 6 to 9
ms Precision Surveillance transmissions 414 per second. It is
understood that ARC-231 refers to an Airborne VHF/UHF/LOS and DAMA
SATCOM Communications System provided by Raytheon Company of
Waltham, Mass., that supports airborne, multi-band, multi-mission,
secure anti-jam voice, data and imagery transmission and provides
network-capable communications in a compact radio set. It will be
readily appreciated that any suitable communication system can be
used.
[0034] Certain waveforms are receive only for the aircraft, and in
the configuration shown in FIG. 2, reception is blocked when
transmitting is required. Therefore the amount of time the aircraft
must listen to the ground transmissions must be taken into
consideration. A variety of information can be broadcast using
these waveforms. Some transmissions provide the location of the
runway; others provide a description of the landing path. Because
of this, the number of time slots occupied by the broadcast from a
particular airport can vary. In addition, the time slots that an
aircraft will choose to receive will depend on what information is
needed at a particular time.
[0035] FIG. 5 shows a format used by the broadcasts for the VHF
Data Broadcast (VDB) to land aircraft. Note that the format is
general in that the application data is listed as 1776 ms max. In
the illustrated embodiment, the number of time slots occupied can
vary from 2 to 8.
[0036] In an exemplary embodiment, only the Joint Precision
Approach and Landing System (JPALS) waveforms require data
transmissions from the aircraft. For an Index 1 type waveform these
interruptions are illustrated in FIG. 6. The interruptions for
Index 2 are similar. It is understood that interruptions occur only
when the aircraft needs to transmit or receive data, otherwise
there is no interference.
[0037] When the JPALS airborne protocol is not logged into the
JPALS Network there will be no voice interruptions until it
attempts to enter the Surveillance Net, about 60 nm from the ship
(or on deck before takeoff). When the aircraft sends the Login
Request 500, it results in an interruption of 7 to 9 ms. If the
aircraft receives a positive response, it begins the interruption
502 of 10 to 13 ms once per second.
[0038] When a Surveillance Login is complete the once per second
interruptions 502 occur until the aircraft reaches 10 nm from the
ship and requests a Precision Surveillance Login. In addition, as
commanded by the ship, a 11 to 15 ms interruption 504 occurs, but
only when the aircraft is logged into the Surveillance Net (not the
Precision Surveillance Net). It continues the once per second
transmissions until it receives a Precision Surveillance time slot
allocation and Precision Surveillance Login is complete.
[0039] When Precision Surveillance Login is complete, the air
traffic control system adds five additional 10 to 13 ms
interruptions 506 per second. For Index 1 the time between
Precision Surveillance Downlink transmissions is 200 ms or a 5 Hz
steady rate. For Index 2 the average rate is 5 Hz, but some of the
times vary from 200 ms (192.4, 153.8, 196.2, 157.6, 207.6, 246.2,
203.8, 242.4, and 196.2). This results in frequencies between 4 and
6.5 Hz. Thus, to transmit the JPALS responses, the aircraft needs
to transmit from 1 to 6 times per second. Normally the
interruptions will be every 200 ms (Precision Surveillance with one
of the intervals containing a second interruption), but the
interruptions are of a duration that does not significantly disrupt
the voice.
[0040] FIG. 6 shows exemplary interruptions and dark areas in which
voice can be transmitted. Also shown is the Miller & Licklider
speech interruption pattern that provided intelligible
communication.
[0041] Table 2 shows the amount of interruptions by the JPALS modes
of operation. The durations shown are far short of the typical
shortest speech phoneme of 40 ms, so the listener normally hears
enough of each syllable to grasp the information.
TABLE-US-00002 TABLE 2 Interruption of Voice by JPALS SRGPS
Transmit Data % Mode Duration Frequency Interruption Not Logged In
None 0 0 Surveillance Login 7 to 9 ms 1 to 20 per sec <1%
Precision Surveillance 10 to 13 ms 1 to 2 per sec <3% Login
Precision Surveillance 10 to 13 ms 6 per second <8%
Operation
[0042] In 1950, Miller and Licklider (J. Acoust. Soc. Am. 22:
167-173, 1950), which is incorporated by reference, investigated
the effects of replacing syllables of speech with silence. Their
results showed that periodic interruption of speech (50%
on-and-off) resulted in a small decline in intelligibility if the
rate of interruption was between 10 to 100 Hz. It is understood
that any suitable periodic speech interruption scheme that provides
acceptable speech recognition can be used. In an exemplary
embodiment, for transmit interruptions, conditions are between 1
and 10 Hz, but the interruptions are significantly shorter than
those disclosed by Miller and Licklider.
[0043] In the SRGPS waveforms, up to 52% of the time is dedicated
to receiving packets. For VDB from 25% to 100% of the time can be
dedicated to that task.
[0044] The shortest time associated with the VDB waveform is a 62.5
ms slot time, with eight slots organized into a half-second frame.
If a transmit/receive timing pattern is arranged such that one slot
is allocated to listen for data, followed by four slots to transmit
voice, then each slot is available to listen for data at least once
every two seconds, and the aircraft always has data from the ground
that is no more than two seconds old. For VDB, there is a five
second constraint on missed messages during landing, so the two
seconds of missed data in this proposed timing should not degrade
operational availability during landing.
[0045] Experience with interrupted speech has shown that varying
the rate of interruption gives a result that is preferred by the
user over interruptions that occur at a fixed rate when all other
factors are equal. Therefore, a system that interrupts the speech
with a randomized pattern is preferred.
[0046] This pattern is tailored for receive-only waveforms like
VDB. To apply it to the SRGPS Index Formats it could be used as is,
or tailored to them. For VDB, it can be assumed that all time slots
can be occupied, but for the Index Formats, about 50% of the time
is available. This means that the format can be tailored to have
less outage of the data or more time dedicated to voice, or a
combination of both.
[0047] In an exemplary embodiment, the system speeds up the voice
using signal processing, so that it fits within the available
transmit interval. For example, a Phase Vocoder uses an FFT process
that allows time compression of speech without changing pitch. In
this case the speech needs a 35% speed up to allow the speech to be
transmitted in the 232.5 ms available. A 128-point FFT produces the
conversion. At 8,000 samples per second this occupies 16 ms, which
allows five conversions during the off time. This information is
stored until transmission is allowed and the final portion is
transmitted at the end of the time. This method also requires some
additional delay to allow for sampling, conversion and
reconstruction.
[0048] In a further embodiment, the transmitting radio makes
real-time decisions, evaluating the transmit voice by inserting a
delay of some tens of milliseconds. This delay allows a signal
processor to evaluate the audio for speech and determine what to
transmit first when the channel is available. If there is no
intelligence in that portion of time it may be safely discarded,
but if there is speech present, the signal processor can decide to
time compress the speech, if necessary. The interruptions may also
be tailored to occur for time slots that need to be monitored,
based on knowledge of what time slots are in use for this
particular airport. Omitting interruptions for unused time slots,
will clearly improve intelligibility, so only the worst case needs
to be evaluated.
[0049] FIG. 7 shows an exemplary timing diagram. The boxes in the
top line show time slots dedicated to transmitting or receiving
data and gaps between them available for voice. A voice signal will
be initiated at a random time with respect to the data, and this is
shown as the Push-to-Talk (PTT) signal on the second line. When
this occurs the voice may be processed in two ways. Line 3 shows a
direct approach wherein the voice is buffered in numbered time
slots. The buffered voice is transmitted when the channel is
available as shown on Line 4 with interruptions of the voice when
the channel is needed for data. The speech arrives at the receiving
terminal, but with gaps as a result of the time taken to transmit
or receive data, and with some delay because of the buffering. A
second approach is to compress the voice so that it can be sent in
its entirety in the reduced time available. Line 5 shows the
compressed speech from Line 3 being buffered and transmitted in
segments that are shorter than the original.
[0050] Table 3 "JPALS Waveforms and Interlacing Options" provides a
comparison of the range of the impact on the voice and data
waveforms for the configurations shown in FIGS. 1, 2 and 3. For
Shared Transmitter and Antenna configurations, if data has
priority, no data is lost, except for reception errors. The third
column applies when a conflict occurs between reception and
transmission. This happens intermittently for a frequency hopping
mode in which the frequency separation between the two services is
too small to provide sufficient isolation. Installations may exist
in which a transmitter needs to be shared and the resources to
provide isolation cannot be installed. The percentages of
interruption shown assume that 2 milliseconds are required to
switch the audio off or on.
TABLE-US-00003 TABLE 3 JPALS Waveforms and Interlacing Options
Implementation Option Two Shared Independent Data Independent
Transmitter Receivers or Format Radios and Antenna Transmitter
SRGPS No Interruptions 6% of Downlink Up to 26% of Index 1
Interruption Downlink Voice No Uplink Voice 6% of Interruption
Uplink Voice No Data Interruption Up to 2 seconds Data Interruption
SRGPS No Interruptions 8% Downlink Voice Up to 26% of Index 2
Interruption Downlink Voice No Uplink Voice 8% of Interruption
Uplink Voice No Data Interruptions Up to 2 seconds Data
Interruption LAAS No Interruptions No Downlink Voice Up to 26% of
(VDB) Interruptions Downlink No Uplink Voice Voice Interruption
Interruptions No Uplink Voice No Data Interruptions Interruption Up
to 2 seconds Data Interruption
[0051] Having described exemplary embodiments of the invention, it
will now become apparent to one of ordinary skill in the art that
other embodiments incorporating their concepts may also be used.
The embodiments contained herein should not be limited to disclosed
embodiments but rather should be limited only by the spirit and
scope of the appended claims. All publications and references cited
herein are expressly incorporated herein by reference in their
entirety.
* * * * *